1. Field Of The Invention
This invention relates to a rapid high-resolution test method and apparatus for anticorrosion performance testing of aqueous protective fluids.
2. Background Of The Invention
Aqueous protective fluids contain oil preparations and emulsions of corrosion inhibitors dispersed in water. Organic protective oils feature good anticorrosion performance and easy removal, thus have a wide use. However, because they are water insoluble, organic protective oils cause considerable environmental pollution and are regulated by many industrialized countries. Aqueous protective fluids, on the other hand, cause few environmental pollution and, even though having relatively poor anticorrosion performance, they are widely used as lubricants for metal materials, as grinding fluids for temperature control during cold processing, and as corrosion protectors during manufacture and short-term storage of metal materials. As various countries become more and more environmentally conscious and intensify their efforts to monitor and protect the environment, aqueous protective fluids will gain popularity.
Currently, although many various types and brands of aqueous protective fluids are commercially available, the testing methods generally applied to evaluate anticorrosion performance include the ISO salt-spray method, humidity test, atmospheric corrosion rest, scrap iron test and laminated test. However, it is difficult to obtain accurate results using those methods for aqueous protective fluids and only qualitative result can be obtained. In addition, known testing methods require long testing times. Therefore, a rapid method for testing of anticorrosion performance of aqueous protective fluids having a high resolution, as well as a corresponding test apparatus for a more efficient testing is needed to satisfy the market demand and the scientific research of various countries. A method for testing the anticorrosion ability of protective oils with wire beam electrode, was recently described in “Research of anticorrosion performance of protective oil with wire beam electrode” China Materials Protection, 1996, 29(4): 9-10; “Influencing factors on the anticorrosion performance of protective oil and characteristics of metal corrosion under oil film” Journal of Chinese Society for Corrosion and Protection, 1999, 19(3): 179-184; and “Discussion on the partial corrosion of metals under oil film” Corrosion science and Protection Technology, 2000, 12(1): 30-31. This method employs a wire beam electrode sensor, which is first coated with protective oils and is then inserted into a corrosive solution of NaCl (5%) to test the anticorrosion performance of the oil. Even though this method can be performed easily and precisely, it is not suitable for aqueous protective fluids. This is because once a sensor is inserted into an water-based sodium chloride solution, aqueous protective fluids would most likely dissolve in the testing medium before its anticorrosion performance could be assessed.